Eurydice tridentata, Jones, David Alan & Nithyanandan, Manickam, 2012

Jones, David Alan & Nithyanandan, Manickam, 2012, Taxonomy and distribution of the genus Eurydice Leach, 1815 (Crustacea, Isopoda, Cirolanidae) from the Arabian region, including three new species, Zootaxa 3314, pp. 45-57 : 48-51

Eurydice tridentata sp. nov.

( Figs. 2 , 4 d–f)

Eurydice inermis . Bruce & Jones 1978: 397, fig. 6h (not E. inermis Hansen, 1890 ).

Material examined. Holotype. Male ( SMF 34843): sta. RS112 near Eilat, Israel, Red Sea, ichthyoplankton, coll. L. Fishelson, 4 Feb. 1985.

Paratypes: 3 males, 2 females ( SMF 34844): sta. RS112 near Eilat, Israel, Red Sea, ichthyoplankton, coll. L. Fishelson 4 Feb. 1985, same locality as type material 3 males, 2 females R138 ( SMF 39703), R20 1 male ( SMF 39704), RS136 1 male, 3 females, juv. ( SMF 39705) coll. L. Fishelson, 1986.

Description. Male holotype: Body, 4.8 mm in length, 3.2 times as long as greatest width at pereonite 5. Cephalon anterior margin rounded, eyes well developed with 7 ocelli horizontally and 5 vertically. Coxae 2–7 with acute angles at posterolateral margins, those of 6–7 produced. Pleonites 2–5 equal in length, pleonite 1 narrow, half length of others. Ventral margins of pleonites 2–5 acute, posterior margin of pleonite 5 straight. Pleotelson 1.3 times wider than long and 4.6 times wider than posterior margin which is truncate and bordered by pronounced teeth. Posterior margin bears 7 apical teeth with the 3 central teeth pronounced; 6 plumose and 2 simple marginal setae are present.

Antennule reaching to posterior margin of pereonite 3, peduncle articles 2 and 3 subequal in length, each bearing a single seta on anterior margin; flagellum of 4 articles, article 1 equal in length to articles 2–4 combined; all articles bearing elongate aesthetascs; flagellar article 4 with 5 terminal setae, one of which is stiff and is twice the length of the combined antennular articles.

Antenna reaching to midlength of pleotelson; length of peduncular articles 1 and 2 combined just exceeds length of article 3; article 4 just shorter than combined length of articles 1–3. Article 2 anterodistal angle with 3 simple setae, article 3 with 3 setae and article 4 with 8 anterior marginal setae. Flagellum with 23 articles, proximal articles half the length of distal articles; each article with 2 long and 1 short setae on anterodistal angle and a plicate process on posteroproximal angle. Setae on article 21 over half length of article 22, terminal seta equal in length to last 3 flagellar articles.

Mandible spine row with 6 spines; molar process anterior margin with 17 spines. Terminal article of mandibular pulp 5 times as long as broad with 9 setae. Article 2 with 2 long setae on posterodistal angle, reaching beyond apex of palp. Maxillule lateral lobe with 13 spines on gnathal surface, medial lobe with 3 stout circumplumose setae and 2 simple setae. Maxilla as for other species in the genus (not figured). Maxilliped palp with all articles entire, terminal article of palp with 10 simple setae; endite with 1 plumose and 2 simple setae.

Pereopod 1 moderately setose with robust seta opposing dactylus half length of dactylus; posterior margin of ischium with 2 robust setae. Merus anterodistal angle without robust setae but with 9 simple setae; posterior margin with 5 robust setae. Pereopod 2 similar but with robust seta opposing dactylus only one third length of dactylus. Two robust setae on posterior margin of ischium and 4 on posterior margin of merus, anterodistal margin with no robust setae but 11 simple setae. Pereopod 3 with 2 robust setae on posterodistal margin of propodus; merus with 3 robust setae on posterodistal margin; carpus with 4 robust setae on posterodistal margin and 2 on posterolateral margin. Ischium with 4 robust setae on posterodistal margin and one group of 2 on posterolateral margin; basis with a single robust seta on posterodistal margin and 5 simple setae. Pereopod 7 setose, propodus anterior margin with 6 robust and 4 simple setae; posterior margin with 7 robust and 8 simple setae. Merus with 8 robust and 8 simple setae on the anterior margin and 7 robust and 16 simple setae on the posterior margin. Ischium with 6 robust setae and 9 simple setae on the anterior margin and 5 robust and 6 simple setae on the posterior margin.

Pleopod 1 endopod shorter and narrower than exopod; endopod with 25 and exopod with 30 plumose setae; exopod 1.25 times wider than endopod. Pleopod 2 exopod with 25 and endopod with 21 plumose setae. Appendix masculina of even width, slightly curved, terminating in a strong pointed process, distal third covered with microtrichs and extending beyond apex of endopod by one fifth of its length. Uropod endopod 1.3 times length of exopod bearing 10 plumose setae on posterior margin and 6 simple setae on lateral margin; exopod triangular with posterior margin straight and 6 setae on laterodistal angle and 7 plumose setae plus 2 simple setae on posterior margin; extending to posterior margin of pleotelson.

Female: As for male but body broader, antennule shorter reaching posterior margin of pereonite 2; antenna shorter, reaching posterior margin of pereonite 4.

Colour. Brown in alcohol with large black chromatophores on dorsal surface of body and ventrolateral surfaces of pleonites 1–3.

Remarks. The truncate posterior margin of the pleotelson has 7 apical teeth, central 3 prominent, no robust setae, but 6 plumose and 2 simple setae. These characters together with the appendix masculina with a straight pointed apex diagnose E. tridentata sp. nov. Comparison of present material with Bruce & Jones (1978, fig 6h) Eurydice ? inermis shows that the appendix masculina of material from Yanbu, Saudi Arabia is similar to that of E. tridentata and not E. inermis Hansen. The rounded posterior pleotelson margin with 6–9 apical teeth, shorter length of antennae and absence of flagellar plicate processes in E. inermis further separates this species from E. tridentata . The only other species with a truncate pleotelson posterior margin and male antennae reaching the pleotelson is E. orientalis Hansen, 1890 . Although the pleotelson posterior margin dentition of this species ( Bruce 1986) is very similar to that of E. tridentata , the three central teeth are prominent in E. tridentata and only 6 plumose and two simple setae are present. The terminal process of the appendix masculina is angled and blunt in E. orientalis , but straight and pointed in E tridentata . In E. orientalis the antennule flagellum reaches no further than pereonite 1, but reaches pereonite 3 in E. tridentata , and the antennal flagellum reaches the mid pleotelson in E. tridentata but reaches the end of the pleotelson in E. orientalis .

Etymology. The specific name recognises the pronounced three central teeth on the pleotelson posterior margin.

Figures

FIGURE 2. Eurydice marzouqui sp. nov. Holotype (SMF 34840): a, b, paratype (SMF 34841) 3: c – 1. a, lateral view; b, dorsal view; c, antennule; d, antennal peduncle; e, antenna; f, mandibles; g, maxillule; h, maxilla; i, maxilliped palp; j, pereopod 1; k, pereopod 3; l, pereopod 7. Horizontal scale = 1.0 mm, vertical scale = 0.1 mm.

FIGURE 4. Eurydice marisrubri sp. nov. Holotype (SMF 34845): a, b, paratypes (SMF 34846) Ƥ: c – m. a lateral b, dorsal view; c, antennule; d, antennal peduncle; e tip of antenna; f mandible; g, maxillule; h, maxilla; i, maxilliped palp; j, pereopod 1; k, pereopod 2; l, pereopod 3; m, pereopod 7. Horizontal scale = 1.0 mm, vertical scale = 0.1 mm.